Rapid exchange (“monorail”) catheters typically comprise a relatively short guide wire lumen provided at a distal end section thereof, and a proximal guide wire exit port located between the catheter's distal and proximal ends. This arrangement allows exchange of the catheter over a relatively short guide wire, in a manner which is simple to perform and which can be carried out by a single physician. Rapid exchange catheters have been extensively described in the art, for example, U.S. Pat. No. 4,762,129 (to Bonzel), U.S. Pat. No. 4,748,982 (to Horzewski) and EP0380873 (to Enger).
Rapid exchange catheters are commonly used in Percutaneous Transluminal Coronary Angioplasty (PTCA) procedures, in which obstructed blood vessels are typically dilated by a distal balloon mounted on the catheter's distal end. A stent is often placed at the vessel's dilation zone to prevent reoccurrences of obstruction therein. The dilation balloon is typically inflated via an inflation lumen which extends longitudinally inside the catheter's shaft between the dilation balloon and the catheter's proximal end.
The guide wire lumen passes within a smaller section of the catheter's shaft length and it is accessed via a lateral port situated on the catheter's shaft. This arrangement, wherein the inner tube is affixed to the catheter's shaft at the location of its lateral port, usually prevents designers from developing new rapid exchange catheter implementations which require manipulating the inner shaft. For example, extending or shortening the catheter's length during procedures may be advantageously exploited by physicians to distally extend the length of the catheter into a new site after or during its placement in the patient's artery, for example in order to assist with the passage of tortuous vessels or small diameter stenoses, or to allow in-situ manipulation of an inflated balloon at the distal end of the catheter.
The rapid exchange catheters of the prior art are therefore usually designed for carrying out a particular procedure and their implementations are relatively restricted as a consequence of the need for at least one catheter shaft to exit the catheter system laterally, between the proximal and distal ends of said system. Consequently, a need exists for a rapid exchange catheter that could overcome the above mentioned restriction and which would allow expansion of the range of applications of such catheters.
It is therefore an object of the present invention to provide a rapid exchange catheter having an adjustable balloon length and shape which may be modified during a procedure.
It is another object of the present invention to provide a rapid exchange balloon catheter wherein the shape and/or volume of a standard inflated balloon may be adjusted during a procedure.
It is a further object of the present invention to provide a rapid exchange balloon catheter capable of collecting samples and/or debris from the body treated site and reducing the risk of distal embolization of any material that may be dislodged during inflation of the balloon at the treated site.
Other objects and advantages of the invention will become apparent as the description proceeds.